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Geophysical ore guides along the Colorado mineral belt

Open-File Report 67-39

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Abstract

A 40-50-mgal gravity low trends northeast along the Colorado mineral belt between Monarch Pass and Breckenridge, Colorado. The low is probably caused by a silicic Tertiary batholith of lower density than adjacent Precambrian crystalline rocks. Many major mining districts associated with silicic Tertiary intrusives are near the axis of the low. Positive and negative aeromagnetic anomalies are present over the larger silicic Tertiary intrusive bodies. A good correlation exists between the magnetic lows and zones of altered, mineralized porphyry. Apparently, original magnetite in the silicic porphyries has been altered to relatively nonmagnetic pyrite or iron oxides. The regional gravity low aids in defining the limits of the mineral belt, and the magnetic lows over the porphyries indicate specific alteration zones and the possibility of associated mineral deposits.

Additional Publication Details

Publication type:
Report
Publication Subtype:
USGS Numbered Series
Title:
Geophysical ore guides along the Colorado mineral belt
Series title:
Open-File Report
Series number:
67-39
Edition:
-
Year Published:
1967
Language:
ENGLISH
Publisher:
U.S Geological Survey],
Description:
13 p. ill., maps ;28 cm.